Well water commonly contains naturally occurring mineral contaminants. Iron, sulfur, and manganese frequently are found in well water giving undesirable odors and taste to the water. These mineral contaminants may also stain plumbing fixtures and corrode pipes.
Mineral contaminants are commonly removed from water by entraining air in the raw water and passing the aerated water through a bed of calcium carbonate or dolomite to raise the pH level of the water and facilitate precipitation of the undesirable minerals. The increased pH water may then be passed through one or more filter media to remove the precipitated contaminants. Commonly oxygen is added to the raw water by passing the water through a pipe section of decreasing cross-sectional area with an air inlet known as a venturi nozzle.
Water treatment apparatuses employing venturi nozzles for aeration of raw water present certain difficulties in service and operation. Strainers will commonly have to be installed upstream of the venturi nozzle to remove sediment in the water which would obstruct the nozzle. Care must be taken to maintain the correct differential pressure between the pump or water supply and the pressure tank of the system to insure proper venturi operation. Furthermore, air introduced upstream of the pressure tank may cause pipes to plug ahead of the pressure tank. Furthermore, the strainer and venturi increase the pressure drop on the water system, which may have an effect on the needed amount of water for backwashing the system.
In addition to the maintenance and operation difficulties associated with venturi nozzles, the venturi may only operate when water is flowing through the system.
Although it is known to substitute an air pump for a venturi in a filtration system, such systems remain dependent on the flow of the water supply to bring fresh oxygen to the water.
What is needed is a water filtration apparatus which supplies the oxygen for the necessary aeration of the raw water to produce satisfactory oxidation of the unwanted minerals without reducing available water pressure and which is not susceptible to clogging or degradation due to water flow.